SOES 3049Vertebrate Palaeobiology:Phylogenetics & Evolution

Lecture 29(a):

Mechanical Properties of

Feathers and their Evolution

Christian Laurent (christian_laurent@live.com)November 2015

What is a feather?Most complex derivatives of the integument to be found in any vertebrate.

Purposes: Flight, thermal insulation, heat shielding, water repellency, camouflage, display.Cover the whole bird apart from feet, beak and eyes.

Not all that have feathers are birds, but all birds have feathers.

Down Contour

Made from

• β-Keratin – fibrous archosaurian protein similar to the mamallian α-keratin found in hair, fingernails and wool.

• Fibres must be contained within an amorphous ‘cement’ – made from Keratin residue monomers. …...think nature’s carbon fibre

evolution

• β – keratins diverged from the earliest common ancestor ~278Ma, we know this from a systematics study on gene sequencing.

• Bird b- keratins ~ 216mya• Extant b-keratins (read:feather) ~143mya

• Feathers originally evolved for insulation and have since been co-opted into flight.

• Feathers originally evolved for insulation and have since been co-opted into flight.

Sinosauropteryx ~130mya

Caudipteryx zoui140mya

Archaeopteryx

• ~147mya• Solnhofen Plattenkalk• 2nd Archaeopteryx

Avian radiation• Feathers lead to the evolution of

flight, a new superniche, which then allowed the formation of hundreds of smaller niches as flight styles / feeding / behaviour / sexual display accommodated flight.

• Explosive and previously unseen rate of divergence.

• The avian phylogeny- even today- is far from a fully resolved bifurcating branch on the tree of life, systematicist have reffered to it as a bush of life.

Second moment

• property of shape that is used to predict resistance to bending and deflection

• Why is a ruler easier to bend in the x-plane than the z

310mm

35mm

2mm

2mm

35mm

35mm

2mm

= 23mm4

= 7145mm4

Parallel axis theorem• I beams• Hollow beams

Fibre layup

Research / application

• Fossils you should look at– Sinosauropteryx– Citipati osmolskae– Sinornithosaurus– Caudipteryx– Microraptor gui

– Note that the filamentous structures in some ornithischian dinosaurs and the pycnofibres found in some pterosaurs are controversial homologues with theropod feathers. Plumage is a convergent homoplaisy but Avian feathers are synapomorphic!

References / Further Reading.Bachmann, T. (2012). Flexural stiffness of feather shafts: geometry rules over material properties. The Journal of Experimental Biology, 215(Pt 3), 405–15. http://doi.org/10.1242/jeb.059451

Laurent, C. M., Palmer, C., Boardman, R. P., Dyke, G., & Cook, R. B. (2014). Nanomechanical properties of bird feather rachises: exploring naturally occurring fibre reinforced laminar composites. Journal of The Royal Society Interface, 11(101). Retrieved from http://rsif.royalsocietypublishing.org/content/11/101/20140961.

Lingham-Soliar, T., Bonser, R. H. C., & Wesley-Smith, J. (2009). Selective biodegradation of keratin matrix in feather rachis reveals classic bioengineering. Proceedings of the Royal Society B: Biological Sciences, 277(1685), 1161–1168. http://doi.org/10.1098/rspb.2009.1980Nudds, R. L., & Dyke, G. J. (2010). Narrow primary feather rachises in Confuciusornis and Archaeopteryx suggest poor flight ability. Science (New York, N.Y.), 328(5980), 887–9.

Prum, R. (2005). Evolution of the Morphological Innovations of Feathers. Journal of Experimental Zoology, 304B(August), 570–579. http://doi.org/10.1002/jez.b.21073.MORPHOLOGICAL